I found out how to make the O2's UI transparent - always found the huge overlay during video playback annoying when using the tactile buttons for FFWD/REW (a bug that was introduced after firmware 1.27 and never fixed).

I made the main screen with large icons transparent as well, so videos show on it, since one can't go straight back from the file list to the video screen, but has to do some idiotic 3-step turning instead. At least one doesn't miss the video that way...

Since there's no way to change some of the most important/annoying colors, I worked with them instead of against them. Result is that I used a lot of blue (since text colors and highlight selectors aren't changeable) and got rid of most of the kindergarten colors found in the awful UI. Still a lot of mismatched blue hues left, but that's beyond repair, beyond the scope of what can be done with GDKPEX.

Also made the speed/timestretch numbers (except default 1.0) in warning colors, in case one inadvertently taps them. That's for both, audio and video mode. I never want to speed a video up or use A-B repeat on it on purpose, and I sometimes touch those damn useless on-screen buttons by accident. Now they at least give a visual clue as to why sound/video appears wrong.

Other than that, there's lots of subtle changes with icons, spacers, fonts (as far as possible). I replaced aliased icons wherever feasible with solid outlined ones, since they didn't look good on the video overlay screen.